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CN106556822A - Spaceborne Sliding spotlight SAR pointing accuracy Orbital detection method - Google Patents

Spaceborne Sliding spotlight SAR pointing accuracy Orbital detection method Download PDF

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Publication number
CN106556822A
CN106556822A CN201610986828.8A CN201610986828A CN106556822A CN 106556822 A CN106556822 A CN 106556822A CN 201610986828 A CN201610986828 A CN 201610986828A CN 106556822 A CN106556822 A CN 106556822A
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control point
imaging
ground control
target0
satellite
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CN106556822B (en
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姜岩
薛伶玲
刘佩东
王意军
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Shanghai Institute of Satellite Engineering
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Shanghai Institute of Satellite Engineering
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/88—Radar or analogous systems specially adapted for specific applications
    • G01S13/89—Radar or analogous systems specially adapted for specific applications for mapping or imaging
    • G01S13/90—Radar or analogous systems specially adapted for specific applications for mapping or imaging using synthetic aperture techniques, e.g. synthetic aperture radar [SAR] techniques
    • G01S13/904—SAR modes
    • G01S13/9056—Scan SAR mode
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/40—Means for monitoring or calibrating
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/88—Radar or analogous systems specially adapted for specific applications
    • G01S13/89—Radar or analogous systems specially adapted for specific applications for mapping or imaging
    • G01S13/90—Radar or analogous systems specially adapted for specific applications for mapping or imaging using synthetic aperture techniques, e.g. synthetic aperture radar [SAR] techniques

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  • Engineering & Computer Science (AREA)
  • Remote Sensing (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Radar Systems Or Details Thereof (AREA)

Abstract

The invention discloses a kind of spaceborne Sliding spotlight SAR pointing accuracy Orbital detection method, comprises the following steps：Ground control point is selected, absolute location coordinates are PTarget0；According to satellite current orbit position PSatellite0It is controlled top moment orbital position P excessively a littleSatellite1(WGS84 coordinate systems) is forecast；Carry out SAR imaging relevant parameters to calculate, relative position coordinates P of the control point in imaging belt are calculated according to imaging parametersRelative0；Satellite is crossed top and known control point area is irradiated and data down transmission, and ground application system receiving data simultaneously carries out the calculating of high accuracy Doppler center and imaging processing；Ground application system carries out geometry location to image according to navigation data and ephemeris parameter, intercepts image by imaging belt width design load；Control point known to recognizing on image, calculates its relative position coordinates P in the sceneRelative1.The present invention can the spaceborne Sliding spotlight SAR pointing accuracy of effectively solving Orbital detection and evaluation problem, effective guarantee user for required target SAR image obtain precision.

Description

Spaceborne Sliding spotlight SAR pointing accuracy Orbital detection method
Technical field
The present invention relates to communication technical field, in particular it relates to a kind of spaceborne Sliding spotlight SAR pointing accuracy Orbital detection Method.
Background technology
Satellite-borne synthetic aperture radar (Synthetic Aperture Radar, SAR) is a kind of to lead all-time anf all-weather Dynamic earth observation systems, in land resources investigation, the important application that aspect has been played such as survey and draw, prevent and reduce natural disasters.Into 21 Since century, satellite-borne SAR technology quickly grows.Satellite-borne SAR resolution more and more higher, the TerraSAR satellites highest of Germany are differentiated Rate reaches 1 meter, and the Cosmo-skymed resolution of Italy has also reached 1 meter.Due to resolution and the paradox of imaging bandwidth, Resolution is improved and causes imaging bandwidth to reduce (the imaging bandwidth of 1 meter of resolution model of TerraSAR satellites only has 5 kilometers).And Imaging bandwidth is little, declines can the ability that SAR wave beams aimed at and captured target, affect the accuracy of satellite-borne SAR object observing With it is ageing.
Here the concept of satellite-borne SAR pointing accuracy is proposed, pointing accuracy satellite-borne SAR is defined as into in-orbit by sight of both working out a scheme Survey the levels of precision for determining Place object.Pointing accuracy is divided into distance to pointing accuracy and orientation pointing accuracy.Pointing accuracy By satellite orbital position prediction error, start moment error, oblique distance measurement error, SAR antenna beams error in pointing and the earth The impact of the factors such as model vertical error.Satellite-borne SAR pointing accuracy is different from positioning precision, aims at emphasis and describes to target The accuracy of area echo data acquisition, and position and be indifferent to whether accurate obtained data are, the figure of data has been obtained by all means As carrying out position resolving.
With regard to the pointing problem of satellite-borne SAR, Curlander analyzes satellite orbital position error, SAR clocking errors, tiltedly Ripple is proposed away from impact of the factor such as measurement error and earth model vertical error to target location, Marco Schwerdt et al. The Orbital detection and modification method of Shu Zhixiang, oblique distance Orbital detection and modification method.Research above is only limitted to affect pointing accuracy Factorial analysiss, and the Orbital detection method of individual effect factor.And for the complete Orbital detection method of pointing accuracy, And analyze and evaluate the means of pointing accuracy from the full link comprehensive system in star ground and temporarily also do not see.
The content of the invention
For defect of the prior art, it is an object of the invention to provide a kind of spaceborne Sliding spotlight SAR pointing accuracy exists Rail method of testing.
According to the spaceborne Sliding spotlight SAR pointing accuracy Orbital detection method that the present invention is provided, comprise the steps：
Step S1：Ground control point is selected, the absolute location coordinates of ground control point are PTarget0, control on the ground Point places calibrater；
Step S2：According to satellite current orbit position PSatellite0Carry out the corresponding top moment track position excessively of ground control point Put PSatellite1With top moment T excessivelyTarget0Forecast；
Step S3：Based on top moment orbital position P excessivelySatellite1The imaging parameters for carrying out synthetic aperture radar SAR are calculated, Relative position coordinates P of the ground control point in imaging bandwidth are calculated according to imaging parametersRelative0；
Step S4：In the top moment T excessively of satelliteTarget0To passing under ground control point irradiation and navigation data, ephemeris parameter, Ground application system receives navigation data and ephemeris parameter and carries out the calculating of high accuracy Doppler center and imaging processing；
Step S5：Ground application system generates image to imaging processing according to the navigation data and ephemeris parameter of satellite and carries out Geometry location, intercepts image by imaging belt width design load；
Step S6：Ground control point is recognized on image, ground control point relative position coordinates in the picture are calculated PRelative1；
Step S7：By relative position coordinates PRelative1With relative position coordinates PRelative0Differ from, as test sample One collimating fault；Repeatedly measure and count the average of collimating faultAnd standard deviationTakeTest for pointing accuracy Value.
Preferably, step S2 includes that step is as follows：
Step S2.1：It is P to obtain current orbit positionSatellite0, the time of relevant position is T0；
Step S2.2：The top moment orbital position P excessively of ground control point is carried out using STK softwaresSatellite1During with crossing top Carve TTarget0Forecast.
Preferably, step S3 includes that step is as follows：
Step S3.1：According to top moment orbital position P excessivelySatellite1With the absolute position P of ground control pointTarget0Phase To relation, select a distance to wave beam, distance is θ to beam positionPoint, it is ensured that distance can preferably cover ground to wave beam Face control point；
Step S3.2：Carry out the signal bandwidth of synthetic aperture radar SAR ripple position, pulse width, pulse recurrence frequency, orientation Arrange to scanning angle scope, and according to the signal bandwidth of synthetic aperture radar SAR ripple position, pulse width, pulse recurrence frequency, side Position is to scanning angle range computation range resolution, azimuth resolution, distance to imaging bandwidth WR, orientation imaging bandwidth WA；
Step S3.3, according to distance to imaging bandwidth WRBandwidth W is imaged with orientationAObtain four of the imaging bandwidth Corner location coordinate P1、P2、P3And P4, relative position coordinates P of the ground control point in imageRelative0It is expressed as PTarget0-Pi (i=1,2,3,4) in any one.
Preferably, step S5 comprises the steps：
Step S5.1：Top moment T is being crossed according to navigation data interpolation calculationTarget0Real satellite position PSatellite2；
Step S5.2：According to the delay measurements τ of synthetic aperture radar SAR0, air delay measurements τ1Calculate star ground tiltedly Away from scalar R, R=c (τ0-τ1)/2, thus construct range equation R=| PSatellite2-PTarget1|, PTarget1Aim at for satellite is actual Position；C is the light velocity；
Step S5.3：According to frequency f of Doppler centerDCConstruction Doppler equation fDC=2/ (λ R) × dot (Vst, PTarget1-PSatellite2), VstFor the lower satellite velocities of WGS84 systems, obtain from satellite navigation data, λ is wavelength, and dot () is Dot product；
Step S5.4：Earth model equation is constructed according to the elevation h of ground control pointWherein ReFor Terrestrial equator radius, RpFor earth polar radius Rp=(1-f) (Re+ h), xt、yt、ztFor vector PTarget1Three factors；
Step S5.5：P is gone out according to range equation, Doppler equation and earth model Equation for CalculatingTarget1Value；
Step S5.6：Four corner location coordinate P' of image are calculated according to the design load of imaging bandwidthi=[PTarget1- (PTarget0-Pi)] (i=1,2,3,4), so that it is determined that imaging bandwidth location.
Preferably, ground control point is recognized in the step 6 on image, calculating ground control point is in designed image Relative position coordinates PRelative1, PRelative1It is represented by PTarget0-P'i(i=1,2,3,4).
Compared with prior art, the present invention has following beneficial effect：
1st, present invention firstly provides a kind of method for testing pointing accuracy from the full link comprehensive system in star ground, with opening It is invasive；
2nd, method flow proposed by the invention is clear, be easily achieved, for satellite managing and control system evaluation plan precision has Important guiding is acted on.
3rd, the present disclosure applies equally to band pattern, SCANSAR patterns, beam bunching mode, TOPSAR patterns, MOSAIC patterns Deng SAR mode of operations.
Description of the drawings
Detailed description non-limiting example made with reference to the following drawings by reading, the further feature of the present invention, Objects and advantages will become more apparent upon：
Fig. 1 is Sliding spotlight SAR system earth observation schematic diagram；
In figure, satellite is that right side regards state of flight, and ground control point position is PTarget10, orientation and distance are to imaging belt It is wide to be respectively WAAnd WR, four corner vectors of imaging belt are P1、P2、P3And P4, it is P that satellite crosses top positionSatllite1(predicted value), The top moment is spent for TTarget0(predicted value), crosses top moment satellite vertical with target link with heading.
Fig. 2 is pointing accuracy Orbital detection block diagram of the present invention；
Fig. 3 is actual homing position PTarget1Relative to forecast homing position PTarget0The schematic diagram of deviation；
Fig. 4 is actual homing position PTarget1Relative to forecast homing position PTarget0The 1000 groups of sample statistics rule deviateed Rule figure.
Specific embodiment
With reference to specific embodiment, the present invention is described in detail.Following examples will be helpful to the technology of this area Personnel further understand the present invention, but the invention is not limited in any way.It should be pointed out that the ordinary skill to this area For personnel, without departing from the inventive concept of the premise, some deformations and improvement can also be made.These belong to the present invention Protection domain.
A kind of spaceborne Sliding spotlight SAR pointing accuracy Orbital detection method is present embodiments provided, is comprised the steps：
Step S1, selects ground control point, and in WGS84 coordinate systems, absolute location coordinates are PTarget0, in ground control Point places calibrater, and background area has uniform, flat, low scattering propertiess, and control point signal to noise ratio is more than 64 times of 30dB and surrounding Without strong target in pixel；
Step S2, according to satellite current orbit position PSatellite0It is controlled top moment orbital position excessively a little PSatellite1(WGS84 coordinate systems) is forecast；
Step S3, based on PSatellite1Carry out SAR imaging parameters calculating, including control point available machine time TTarget0, distance to Beam position θPoint, resolution, imaging bandwidth etc., calculate relative position of the ground control point in imaging bandwidth according to imaging parameters Put coordinate PRelative0；
Step S4, crosses top moment T according to satellite is accurateTarget0To make the plan, known ground control point area is shone Penetrate and data down transmission, ground application system receiving data simultaneously carries out high accuracy Doppler center (fDC) calculate and imaging processing；
Step S5, ground application system carry out geometry location to image according to the navigation data and ephemeris parameter of satellite, press Imaging bandwidth design load intercepts image；
Step S6, recognizes known ground control point on image, calculates ground control point relative position in the picture and sits Mark PRelative1；
Step S7, by PRelative1With PRelative0Differ from, as one collimating fault test sample；Repeatedly measure and count The average of collimating faultAnd standard deviationTakeFor pointing accuracy test value.
Further, according to satellite current orbit position P in the step 2Satellite0It is controlled the top moment excessively a little Orbital position PSatellite1(WGS84 coordinate systems) is forecast, as follows including step：
Step S2.1, current orbit position are PSatellite0(WGS84 coordinate systems), the time of relevant position is T0；
Step S2.2, carries out the top moment orbital position P excessively of ground control point using STK softwaresSatellite1(WGS84 sits Mark system) and Covering time TTarget0Forecast.
Further, relative position coordinates of the control point in imaging belt are calculated according to imaging parameters in the step 3 PRelative0, it is as follows including step：
Step S3.1, according to user for the demand (including resolution, imaging bandwidth etc.) of target image, selects Working mould Formula, specifically includes band, slip pack, SCANSAR, TOPSAR etc., here by taking slip beam bunching mode as an example；
Step S3.2, according to satellite position PSatellite1With control point position PTarget0Relativeness, select one it is suitable Distance (be oriented to θ to wave beamPoint), it is ensured that wave beam can preferably cover ground control point；
Step S3.3, carries out SAR Beam position design, modelled signal bandwidth, pulse as input with mode of operation and image demand The radar running parameters such as width, pulse recurrence frequency, orientation scanning angle scope, and according to this computed range to resolution, side Position is to resolution, distance to imaging bandwidth WR, orientation imaging bandwidth WADeng image property index；
Step S3.4, according to WRAnd WADesign result, can obtain the position P of four corners of designed imaging belt1、P2、 P3And P4, as shown in Figure 1, relative position P of the control point in imageRelative0It is represented by PTarget0-Pi(i=1,2,3, 4) any one in.
Further, in step S5, ground application system carries out geometry to image according to navigation data and ephemeris parameter Positioning, intercepts image by imaging belt width design load, comprises the steps：
Step S5.1, is crossing top moment T according to navigation data interpolation calculationTarget0Real satellite position PSatellite2；
Step S5.2, according to SAR system delay measurements τ0And air delay measurements τ1Calculate star ground oblique distance scalar R, R =c (τ0-τ1)/2, thus construct range equation R=| PSatellite2-PTarget1|, PTarget1For the position of the actual aiming of satellite, it is Unknown variable, c are the light velocity；
Step S5.3, according to the doppler centroid f that step 4 is calculatedDCConstruction Doppler equation fDC=2/ (λ R) × dot(Vst,PTarget1-PSatellite2), VstFor the lower satellite velocities of WGS84 systems, obtain from satellite navigation data, λ is wavelength, Dot () is dot product；
Step S5.4, constructs earth model equation according to the elevation h (known quantity) at control pointWherein ReFor terrestrial equator radius, RpFor earth polar radius Rp=(1-f) (Re+ h), xt、yt、ztFor vector PTarget1Three factors；
Step S5.5, according to three above equation, calculates PTarget1Value；
Step S5.6, according to 3.4 section imaging bandwidth design results, calculates four corner location P' of real imagei= [PTarget1-(PTarget0-Pi)] (i=1,2,3,4), are thus imaged bandwidth location and are determined.
Further, known control point is recognized on image in step S6, calculate which relative in designed image Position coordinateses PRelative1, PRelative1It is represented by PTarget0-P'i(i=1,2,3,4).
Further, by P in the step 7Relative1With PRelative0Differ from, as one collimating fault test sample； Repeatedly measure and average statisticalAnd standard deviationTakeFor pointing accuracy test value.
More specifically, accompanying drawing 2 give the present invention implement step：
(1) select ground control point：
Absolute location coordinates are PTarget0(WGS84 coordinate systems), places calibrater at control point, and background area has equal Even, flat, low scattering propertiess, control point signal to noise ratio are more than in 64 times of pixels of 30dB and surrounding without strong target；
(2) cross the forecast of top moment
According to satellite current orbit position PSatellite0It is controlled top moment orbital position P excessively a littleSatellite1(WGS84 Coordinate system) forecast；
2a), current orbit position is PSatellite0(WGS84 coordinate systems), the time of relevant position is T0；
2b), using STK softwares be controlled a little cross top moment orbital position PSatellite1(WGS84 coordinate systems) and mistake Top time TTarget0Forecast.
(3) control point relative position in the imaging belt is calculated with forecast data
Based on PSatellite1Carry out SAR imaging relevant parameters to calculate (including control point available machine time TTarget0, distance is to ripple Shu Zhixiang θPoint, resolution, imaging bandwidth etc.), calculate relative position coordinates of the control point in imaging belt according to imaging parameters PRelative0；
3a), mode of operation (bag is selected for the demand (including resolution, imaging bandwidth etc.) of target image according to user Include band, slip pack, SCANSAR, TOPSAR etc.), here by taking slip beam bunching mode as an example；
3b), according to satellite position PSatellite1With control point position PTarget0Relativeness, select one it is suitable away from Descriscent wave beam (is oriented to θPoint), it is ensured that wave beam can preferably cover control point；
3c), SAR Beam position designs are carried out by input of mode of operation and image demand, modelled signal bandwidth, pulse width, The radar running parameters such as pulse recurrence frequency, orientation scanning angle scope, and computed range divides to resolution, orientation according to this Resolution, distance are to imaging bandwidth WR, orientation imaging bandwidth WADeng image property index；
3d), according to previous step WRAnd WADesign result, can obtain the position P of four corners of designed imaging belt1、 P2、P3And P4, as shown in Figure 1, relative position P of the control point in imageRelative0It is represented by PTarget0-Pi(i=1,2, 3,4) in any one.
(4) target observation and ground imaging processing：
The top moment is spent for T according to satellite is accurateTarget0To make the plan, known control point area is irradiated and data under Pass, ground application system receiving data simultaneously carries out high accuracy Doppler center (fDC) calculate and imaging processing；
(5) ground application system carries out geometry location to image according to navigation data and ephemeris parameter, sets by imaging belt width Evaluation intercepts image：
5a), T is calculated according to lower conduction boat data interpolatingTarget0The real satellite position P at momentSatellite2；
5b), according to SAR system delay measurements τ0And air delay measurements τ1Calculate star ground oblique distance scalar R, R=c (τ0-τ1)/2, thus construct range equation R=| PSatellite2-PTarget1|, PTarget1For the position of the actual aiming of satellite, c is light Speed；
5c), the doppler centroid f for being calculated according to step 4DCConstruction Doppler equation fDC=2/ (λ R) × dot (Vst, PTarget1-PSatellite2), VstFor the lower satellite velocities of WGS84 systems, obtain from satellite navigation data, λ is wavelength, and dot () is Dot product；
5d), earth model equation is constructed according to the elevation h (known quantity) at control pointWherein ReFor Terrestrial equator radius, RpFor earth polar radius Rp=(1-f) (Re+ h), xt、yt、ztFor vector PTarget1Three factors；
5e), according to three above equation, calculate PTarget1Value；
5f), according to 3.4 section imaging bandwidth design results, four corner location P' of real image are calculatedi=[PTarget1- (PTarget0-Pi)] (i=1,2,3,4), are thus imaged bandwidth location and are determined.
(6) known control point is recognized on image, calculate its relative position coordinates P in the sceneRelative1
Control point known to recognizing on image, calculates its relative position coordinates P in designed imageRelative1, PRelative1It is represented by PTarget0-P'i(i=1,2,3,4).
(7) by PRelative1With PRelative0Differ from, as one collimating fault test sample；Repeatedly measure and average statisticalAnd standard deviationTakeFor pointing accuracy test value.
The effect of the present invention is described further with reference to emulation data.
Here sun-synchronous orbit X-band satellite-borne SAR is selected to carry out the simulating, verifying of pointing accuracy Orbital detection method.Star Carry SAR orbit altitude about 600km, SAR antenna sizes are 4 (m, orientation) × 3 (m, distance to), SAR mode of operations select to slide Dynamic beam bunching mode, resolution are designed as 0.6m, and distance is separately designed as 4km and 6km to imaging bandwidth and orientation imaging bandwidth, Point height is controlled for 80m.Affect pointing accuracy each factor value be：Orbital position prediction error 200m, vertical error m are opened Machine moment error 20ms, oblique distance measurement error 5m, 0.04 ° of Beam steering error.Each parameter value is as shown in table 1 above.
1 simulation parameter value of table
Select current time T0For 2016 03 month 01 day 16 when 40 points 50 seconds, satellite orbital position PSatellite0(WGS84 Coordinate system) for (- 293426.77m, -1518882.08m, -6842101.58m).Orbit simulation is carried out using STK softwares, is obtained Moment and satellite position after 24 hours, when respectively 2016 03 month 02 day 16 40 points 50 seconds and (3044738.32m ,- 6275956.74m, -701278.29m), and top moment and position are crossed as theoretical, this segment data is reused in simulations, Right side is regarded direction of visual lines and the earth model intersection point (elevation 80m) of 40 ° of downwards angle of visibilities as control point position PTarget0。
According to table 1, with 200m as standard deviation, 1000 groups of data are randomly generated, as the input position skew of STK forecast (with PSatellite0For starting point), produce 1000 groups of Covering time T for crossing control pointTarget0Predicted value and satellite position predicted value PSatellite1.Similarly, according to parameter value in table 1,1000 groups of vertical errors, start moment error, tiltedly are randomly generated respectively Away from measurement error and Beam steering error.1000 Beam position designs are carried out using sample above and radar parameter is calculated.Signal band Wide to select as 420MHz, range resolution is designed as 0.58m, and distance is to a width of 4km of imaging belt；Azimuth resolution is 0.6m, scanning angle are ± 1.05 °, a width of 6km of orientation imaging belt.1000 composition image-tape position (P can be obtained1、P2、P3With P4) and PRelative0Value (P used in emulationTarget0-P1Calculate).
Satellite crosses top and according to above-mentioned design parameter in TTarget0Moment irradiates control point, and data down transmission send Ground Application system System is completed to process and is positioned, and obtains actual homing position PTarget1.Image is intercepted according to imaging bandwidth design load, so as to obtain 1000 groups of P'i(i=1,2,3,4), on image recognize control point respectively, are calculated 1000 groups of PRelative1(used in emulation PTarget0-P'1Calculate).By PRelative1With PRelative0Make difference and count, obtain averageStandard deviationThen pointing accuracyActual homing position PTarget1Relative to forecast homing position PTarget0The schematic diagram of deviation is as shown in figure 3,1000 groups of sample statistics rules are as shown in Figure 4.
Above the specific embodiment of the present invention is described.It is to be appreciated that the invention is not limited in above-mentioned Particular implementation, those skilled in the art can make various modifications or modification within the scope of the claims, this not shadow Ring the flesh and blood of the present invention.

Claims (5)

1. a kind of spaceborne Sliding spotlight SAR pointing accuracy Orbital detection method, it is characterised in that comprise the steps：
Step S1：Ground control point is selected, the absolute location coordinates of ground control point are PTarget0, put in the ground control point Put calibrater；
Step S2：According to satellite current orbit position PSatellite0Carry out the corresponding top moment orbital position excessively of ground control point PSatellite1With top moment T excessivelyTarget0Forecast；
Step S3：Based on top moment orbital position P excessivelySatellite1The imaging parameters for carrying out synthetic aperture radar SAR are calculated, according to Imaging parameters calculate relative position coordinates P of the ground control point in imaging bandwidthRelative0；
Step S4：In the top moment T excessively of satelliteTarget0To passing under ground control point irradiation and navigation data, ephemeris parameter, ground Application system receives navigation data and ephemeris parameter and carries out the calculating of high accuracy Doppler center and imaging processing；
Step S5：Ground application system generates image to imaging processing according to the navigation data and ephemeris parameter of satellite and carries out geometry Positioning, intercepts image by imaging belt width design load；
Step S6：Ground control point is recognized on image, ground control point relative position coordinates in the picture are calculated PRelative1；
Step S7：By relative position coordinates PRelative1With relative position coordinates PRelative0Differ from, as the one of test sample Collimating fault；Repeatedly measure and count the average of collimating faultAnd standard deviationTakeFor pointing accuracy test value.
2. spaceborne Sliding spotlight SAR pointing accuracy Orbital detection method according to claim 1, it is characterised in that described Step S2 includes that step is as follows：
Step S2.1：It is P to obtain current orbit positionSatellite0, the time of relevant position is T0；
Step S2.2：The top moment orbital position P excessively of ground control point is carried out using STK softwaresSatellite1With the top moment excessively TTarget0Forecast.
3. spaceborne Sliding spotlight SAR pointing accuracy Orbital detection method according to claim 1, it is characterised in that described Step S3 includes that step is as follows：
Step S3.1：According to top moment orbital position P excessivelySatellite1With the absolute position P of ground control pointTarget0Relative pass System, selects a distance to wave beam, and distance is θ to beam positionPoint, it is ensured that distance can preferably cover ground control to wave beam Point processed；
Step S3.2：Carry out the signal bandwidth of synthetic aperture radar SAR ripple position, pulse width, pulse recurrence frequency, orientation to sweep Angular range setting is retouched, and according to the signal bandwidth of synthetic aperture radar SAR ripple position, pulse width, pulse recurrence frequency, orientation Scanning angle range computation range resolution, azimuth resolution, distance are to imaging bandwidth WR, orientation imaging bandwidth WA；
Step S3.3, according to distance to imaging bandwidth WRBandwidth W is imaged with orientationAObtain four corners of the imaging bandwidth Position coordinateses P1、P2、P3And P4, relative position coordinates P of the ground control point in imageRelative0It is expressed as PTarget0-Pi(i= 1,2,3,4) in any one.
4. spaceborne Sliding spotlight SAR pointing accuracy Orbital detection method according to claim 1, it is characterised in that described Step S5 comprises the steps：
Step S5.1：Top moment T is being crossed according to navigation data interpolation calculationTarget0Real satellite position PSatellite2；
Step S5.2：According to the delay measurements τ of synthetic aperture radar SAR0, air delay measurements τ1Calculate star ground oblique distance mark Amount R, R=c (τ0-τ1)/2, thus construct range equation R=| PSatellite2-PTarget1|, PTarget1For the position of the actual aiming of satellite Put, c is the light velocity；
Step S5.3：According to frequency f of Doppler centerDCConstruction Doppler equation fDC=2/ (λ R) × dot (Vst,PTarget1- PSatellite2), VstFor the lower satellite velocities of WGS84 systems, obtain from satellite navigation data, λ is wavelength, and dot () is dot product；
Step S5.4：Earth model equation is constructed according to the elevation h of ground control pointWherein ReFor the earth Equatorial radius, RpFor earth polar radius Rp=(1-f) (Re+ h), xt、yt、ztFor vector PTarget1Three factors；
Step S5.5：P is gone out according to range equation, Doppler equation and earth model Equation for CalculatingTarget1Value；
Step S5.6：Four corner location coordinate P' of image are calculated according to the design load of imaging bandwidthi=[PTarget1- (PTarget0-Pi)] (i=1,2,3,4), so that it is determined that imaging bandwidth location.
5. spaceborne Sliding spotlight SAR pointing accuracy Orbital detection method according to claim 4, it is characterised in that described Ground control point is recognized on image in step 6, relative position coordinates of the ground control point in designed image are calculated PRelative1, PRelative1It is represented by PTarget0-P'i(i=1,2,3,4).
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